How California Reservoirs’ Water Levels Changed After Back-To-Back Storms

According to the California Department of Water Resources (DWR), the water levels in many of the state’s major reservoirs went up after three back-to-back storms hit California over the last 10 days. 

This winter, California got a lot more rain and snow than usual because of big storms and “atmospheric rivers” bringing loads of rain and snow in January. 

Consecutive Storms Replenishes California’s Reservoirs

These three consecutive storms recently brought even more rain and snow across the state, filling up many of California’s reservoirs. 

Last year, more than a dozen storms played a vital role in easing California’s severe drought problem and refilled many of the state’s reservoirs. However, these storms also brought devastating floods and landslides. 

Series Of Storms Begin March 22, End March 29th

The series of storms began on March 22, unleashing heavy rain and snow in the northern part of the state. A second storm followed on March 26 and the following weekend, a third and final storm hit the state contributing to widespread heavy precipitation across California.

Last week Friday, the third storm in the series of successive storms brought heavy rain across much of California. 

What Are Atmospheric Rivers?

Atmospheric rivers are defined as “long, narrow regions in the atmosphere—like rivers in the sky— that transport most of the water vapor outside the tropics,” according to the National Oceanic and Atmospheric Administration (NOAA). 

A January 2019 article in Geographic Research Letters defined them as “long, meandering plumes of water vapor often originating over the tropical oceans that bring sustained, heavy precipitation to the west coasts of North America and northern Europe.”

Climate Change Expected To Increase Intensity And Frequency Of Atmospheric Rivers

Other names for the phenomenon include tropical plume, tropical connection, moisture plume, water vapor surge, and cloud band. Pineapple Express storms are the most recognized type of atmospheric rivers, named for the warm, moist air originating in the Hawaiian tropics.

These storms travel across regions like California, the Pacific Northwest, British Columbia, and southeast Alaska. Climate change is expected to heighten the intensity and frequency of these storms, leading to more extreme weather events and floods, particularly in the Western United States and Canada.

Rain Forecast For Carlifornia And Lake Shasta Water Levels

According to a map shared by the NWS, Redding, California—home to Lake Shasta—was forecast to receive up to an inch of rain from the storm. 

Lake Shasta’s water level was recorded at 1,050.47 feet last Friday, approximately 17 feet below full capacity. In the Sacramento region, the heaviest rain was expected to fall on Friday afternoon. 

Storm Triggers Travel Delays And Chain Controls

“Precipitation will continue to spread across the area today through Saturday, with the heaviest expected this afternoon into early Saturday. Here’s a look at the latest forecast rainfall & snowfall totals. Expect mountain travel delays & chain controls,” NWS Sacramento posted on X, formerly Twitter, with the map.

As of last Friday, Lake Shasta’s water levels were 1,050.47 feet, almost 17 feet from full.

Wet Winters Helps City’s Reservoirs Recover

Lake Shasta’s situation got much better since the summer of 2022 when water levels at reservoirs all over the state dropped to worrying levels due to years of drought. 

Last year, the city had an abnormally wet winter that filled up many lakes, and this year’s winter was wet too, helping them recover even more.

High Water Levels Prompt Release Of Billions Of Gallons

Lake Shasta’s levels got so high that water officials had to let out billions of gallons of water because it was too high. Even after letting some out, the lake is still 16 feet higher than last year and 110 feet higher than it was in late March of 2022.

The region might have some dry weather coming up before it starts raining again.

Showers Expected In Sierra Nevada And Shasta County, Valley Stays Dry

“After this system, we will have some clearing at least for the first part of the week,” NWS meteorologist Jeffery Wood told Newsweek. “There’s potential for another weather system to move in toward the end of next week as well.”

The coming weather system might bring showers to the Sierra Nevada mountains and Shasta County’s higher elevation areas, but the valley isn’t likely to see any rainfall.

Rain Boosts Snowpack And Reservoir Levels Across California

The recent increase in precipitation not only raised California’s snowpack levels but also upped the water levels of many major reservoirs in the state, as shown on an interactive DWR chart.

The chart shows that the following reservoirs saw their water levels surge after the storms: Shasta, Oroville, New Bullards Bar, Folsom, Camanche, Trinity, New Melones, Casitas, Castaic, McClure, Millerton, and Pine Flat.

Folsom Lake And Millerton Lake Benefit The Most

The California lakes with the biggest increase are Folsom Lake in Folsom and Millerton Lake in Friant, both going up by 6 percent in their water levels. Folsom Lake went from 66 percent full to 72 percent, which is 115 percent of its historical amount.

Millerton Lake went from 72 percent full to 78 percent, which is 114 percent of its historical amount.  Lake Shasta wasn’t too far behind. The lake’s levels jumped from 87 percent capacity to 92 percent. That’s about 116 percent of its historical average.

Changes In California Lake Levels After Storms

Sadly, Don Pedro Lake and Lake Sonoma levels experienced no increase after the storms. Diamond Valley Lake and Lake Cachuma only experienced a slight decrease in water levels. 

Diamond Valley went from 91 percent pre-storm to 90 percent post-storm. Although, that’s still 120 percent of its usual average. Lake Cachuma dropped from being 102 percent full to 100 percent full because the U.S. Bureau of Reclamation let out water from the lake before the storms.

Precautionary Releases At Lake Cachuma Amid Improved Water Conditions

“We’re making room in Lake Cachuma for forecasted inflows. Precautionary spillway releases totaling 1280 cfs from Bradbury Dam into the Santa Ynez River have begun,” the Bureau of Reclamation for the California Great Basin region posted on X(formerly Twitter) last week.

The improved water condition is good news for California, which has been dealing with years of drought. The drought caused many lakes and reservoirs to drop to worryingly low levels in 2022.